Anyone here converted from 46RE to regular 727?

[Copperhead]

I chopped the OD transmission out of my truck and I'm hoping to bring home my new Torqueflite 3 speed tomorrow. Is there anything I need to be aware of to make this thing work? Or is it a direct bolt in? I've seen murky references to something about spacers between the crank flange and torque converter, but no explanations.

FWIW, I know I'll need a new crossmember, and that my PCM isn't going to be happy. Thats all covered.

[dgc333]

Never heard anything about spacers and such with but could be.

Curious, why would you want to replace the 46RE with a 727?

The 46RE is a 727 with an OD gear hung off the back and electrically controlled govenor.

[Copperhead]

First, after converting to DFI, I'm still stuck with the factory PCM for fuel, gauges, voltage regulation, and shift governing. I want to eliminate all of that. I've already got the alternator and gauges figured out, the fuel will happen as soon as our rails are finished. That leaves the transmission, which I'm taking care of right now.

Second, the OD in the 46RE is a weak unit that you really shouldn't be racing through. It may be good for the occasional street showdown, but not for heavy street/strip use. Yes, I know there's lots of people racing on these things but I firmly believe they're living on borrowed time.

The 46RE also has too much friction loss to be useful to me. In the Dakota world, the people who use the straight 727 typically see a half second knocked off their ET with this mod. (I know I could knock even more off by going with the 904, but I want to tackle one mountain at a time.) I like having OD, but I'm going to install a Gear Vendors OD later on. The planetary style OD has zero friction loss, and GV claims they have no failures at well over 1000hp.

With that GVO in there, I think it will be a blast to make people wonder when they hear the truck go from a dig, "He has an auto - listen to it shift - no wait! It shifted 5 times - it has to be a T56... but it sounded like an auto?!?!"

[John Kunkel]

There are no adapters needed to mate a SB 727 in place of a 46RE. If the factory fuel injection is being eliminated there is no need for the 46RE flexplate, just use one from a 727.

A standard shift PCM should take care of compatibility problem.

[Copperhead]

Thanks for the info John.

The fuel system is the last piece of the puzzle that I'll have left to convert. I'll have to leave the 46RE flexplate on there until I get my fuel rails and other parts. I'll be PCM-free then.

[John Kunkel]

The '96 and later converters/flexplates have a symmetric 90° bolt pattern so, to use a 727 converter with one offset bolt, you'll have to elongate one bolt hole in the flexplate. The 727 bellhousing will also have to be notched for the crank position sensor; use the 46RE as a pattern

[Copperhead]

Thanks again.

One more question, John...

If I was to keep the 46RE in there, is there a way to eliminate the PCM and somehow have the transmission work? Didn't they have a version called the RH that wasn't hooked to the PCM?

[dodger1]

Pre-95 I think - the lock-up was purely hydraulic and the o/d was a simple on-off switch. RH stands for R(ear drive) H(ydraulic)

[Copperhead]

Hydraulic lockup?? Thats bizarre. The first lockup transmissions GM had back in 1981 were electronic. I wonder why Dodge would use something so prehistoric 14 years later.

[John Kunkel]

Originally Posted by Copperhead

If I was to keep the 46RE in there, is there a way to eliminate the PCM and somehow have the transmission work? Didn't they have a version called the RH that wasn't hooked to the PCM?

'96 and later have an electronic governor which prevents controlling the unit with simple toggle switches like the '90-'95 RH models could.

There are some aftermarket stand alone controllers but they're kinda pricey:

http://www.powertraincontrolsolution...content-4.html

[Copperhead]

John, I have another question. I have to order my new torque converter, and its going to be a custom one built to my specs. My builder needs to know if the converter should have balance weights on it. I don't remember what the converter for my 518 had, but it ran perfectly with no vibrations. Since I'm changing not just transmissions but also going to a non-lockup build, I have no idea what to tell the builder.

My motor is a 408 with a forged crank, externally balanced, in case that makes a difference.

[JVMopar]

Your engine would have had a weight on the flex plate. B&M make a flexplate for magnum engines to 727. Most likely your 408 would have been balanced for stock magnum 360 so just get a B&M weighted flex plate and no weights on the converter.

[Copperhead]

Originally Posted by JVMopar

Your engine would have had a weight on the flex plate. B&M make a flexplate for magnum engines to 727. Most likely your 408 would have been balanced for stock magnum 360 so just get a B&M weighted flex plate and no weights on the converter.

I can't use the B&M because I need the notched stock flexplate for the crank trigger. Otherwise my fuel system won't run.

I just checked the flexplate and it has weights on it. It worked perfectly with the stock transmission and converter, so I should be ok with the 727 and an unweighted converter.

Just how do all these weights work together? I understand about balance and all that, but how does the flexplate maufacturer know what the converter guys know, and if the crank is going to work with all this? If I have my next forged crank internally balanced, then what?

[John Kunkel]

If the existing flexplate has weights, the converter bolt pattern is symmetric so you will need top elongate one bolt hole to use a 727 converter.

The amount of weight needed to externally balance the motor is a known quantity, so aftermarket flexplates simulate the balance weight by removing a known amount of weight from the flexplate; the removed weight is 180° from where the weight is needed to balance the internals.

If the engine is later balanced internally, the weights will have to be removed from the flexplate and the damper

[JVMopar]

There isn't enough weight (or room for larger weights) in the cast crankshafts to balance out the rotating assembley. So they add the weights externally. Most Mopar engines with cast cranks were balanced externally.

[Copperhead]

Originally Posted by John Kunkel

If the existing flexplate has weights, the converter bolt pattern is symmetric so you will need top elongate one bolt hole to use a 727 converter.

John,

I just got my converter. I put it on the input shaft and I was test fitting some parts to see if anything had to be modified. It looks like I'll need to change a few things.

First, I see that the 727 does not have the access relief cut into the bottom of the bellhousing. The dustcover off my 46RE doesn't fit the 727 because that relief isn't cut. What dustcover should I use?

Also, I was looking at my torque converter and I saw a stamping on the face. It was a "90" with the degree mark next to it. What does this mean?

[dodger1]

Re: the external balancing - you need to talk to the engine builder/balance shop and find out exactly which flexplate or converter weight value they used to simulate the needed weight when balancing the assembly. Some shops simply weld the appropriate weight to a stock flexplate - which is fine as long as you know what the offset weight value is. You'll need to be sure to use the corresponding flexplate and /or weighted converter.. Don't ask me how I know this, it's too painful to re-tell.

[John Kunkel]

The 90° stamped on the face of the converter means the drive lugs are 90° apart (symmetric bolt pattern) so it will mate to your weighted flexplate with no modifications.

I'm not sure what to do about the dust cover, I would imagine one from an earlier SB 727 would wor

[Copperhead]

I bet my transmission builder has them laying around in piles. I'll stop by his place and take care of that. Thanks again John.

[Copperhead]

And before I forget and look ignorant, thanks to Dodger1 and JVMopar as well.

[Copperhead]

Originally Posted by John Kunkel

The 727 bellhousing will also have to be notched for the crank position sensor; use the 46RE as a pattern.

It looks like I won't need that crank sensor, John. I found out that Accel put a fuel system driver in their DFI product. All I have to do is run a relay and tie the thing in to the factory fuel pump wiring. Actually, I may just use the fuel relay thats already in the factory power distribution block. It is grounded by the PCM to start the fuel system, whereas the DFI system sends a +12v signal out. All I have to do is permanently ground the factory fuel relay, and splice the DFI lead to the + side of the relay, and all should be good. Sound like a plan?

After that, I just need to put a voltage regulator on the alternator, replace the gauges, and I'm PCM free.